Acceleration switches



A ril 28, 1970 E. a. PARKES 5 95-29 ACCELERATION SWITCHES Filed Jan. 13, 1967 United States Patent 0.

3,509,530 ACCELERATION SWITCHES Eric Bernard Parkes, Selly Oak, Birmingham, England,

assignor to Joseph Lucas (Industries) Limited, Birmingham, England, a British company Filed June 13, 1967, Ser. No. 645,660 Claims priority, application Great Britain, July 15, 1966, 31,877/ 66 Int. Cl. B60q 1/50; H01h 35/14 US. Cl. 340-71 1 Claim ABSTRACT OF THE DISCLOSURE This invention relates to acceleration switches intended particularly but not exclusively for use in road vehicles.

A switch according to the invention comprises in com bination a pendulum movable from a rest position in response to acceleration of the switch, a first contact carried by the pendulum, a second contact engageable by the first contact upon movement of the pendulum as a result of acceleration of the switch to complete an electrical circuit, and releasable latch means co-operating with the pendulum and operable as the contacts close to retain the pendulum in a position in which the contacts are closed.

The switch is particularly designed for use in road vehicles for illuminating a lamp at the rear of the vehicle in response to negative accelerations, but in other applications the electrical circuit may give a warning or effect a control in response to either positive or negative accelerations.

The accompanying drawing is a diagrammatic representation of one example of the invention as applied to a road vehicle.

Referring to the drawing, the switch includes a pendulum 1 having a horizontally extending pivot 2 and which carries at its lower end a cam follower 3. The cam follower 3 engages a cam surface 4 on the armature 5 of an electro-magnet 6, the armature 5 being urged towards the cam follower 3 by a leaf spring 7 which also serves to support the armature.

The pendulum 1 further carries a contact 8 which is aligned with a fixed contact 9, and the pendulum is urged in a direction to move the contact 8 away from the contact 9 by a spring 10. The tension in the Spring 10 is adjustable by means of a screw mechanism 11.

The cam surface 4 is formed with a vertical portion 4a which limits the distance by which the pendulum can be moved by the spring 10, an inclined portion 4c and a depression 4b defined between the portions 4a, 40 within which the cam follower 3 seats.

One end of the coil 13 of the electro-magnet is earthed, and its other end is connected through a switch 14 to the negative terminal of the vehicle battery 15, the positive terminal of which is earthed, the switch 14 being closed in response to depression of the accelerator pedal of the vehicle. The contact 8 is connected through a warning lamp 16 to the negative terminal of the battery 3,509,530 Patented Apr. 28, 1970 2 15 and the contact 9 is earthed so that when the contact 8 engages the contact 9 the lamp 16 is energised.

In use, the switch is oriented in a road vehicle so that if the vehicle is subject to a negative acceleration above a predetermined magnitude the pendulum will swing against the action of the spring 10 in a direction to move the cam follower over the cam surface 4. When the contacts 8, 9, engage the lamp 16 is energized through the pendulum 1, and at this stage the follower 3 is engaged with the portion 40 of the cam surface 4, thereby trapping the pendulum and maintaining the contacts 8 and 9 engaged. However, when the driver of the vehicle depresses the accelerator pedal, the switch 14 closes to energize the electro-magnet 6, which moves the armature 5 downwardly against the action of the spring 7, thereby releasing the pendulum 1, which then moves under the influence of the spring 10 until it is arrested by the portion 4a of the cam surface 4. This movement of the pendulum 1 opens the contacts 8, 9 thereby de-energizing the lamp 16.

The sensitivity of the switch to negative acceleration can be adjusted by moving the screw mechanism 11 to vary the tension in the spring 10. The lamp 16 is positioned at the rear of the vehicle so that a warning of such negative acceleration is given to following vehicles.

The pendulum could of course be released in other ways. For example, the switch 14 could be manually operable, speed sensitive, pressure sensitive, or a time delay switch.

Having thus described my invention What I claim as new and desire to secure by Letters Patent is:

1. A warning system for indicating when a road vehicle is decelerating, comprising in combination a pendulum movable from a rest position in response to deceleration of the vehicle, a first contact carried by the pendulum, a second contact engageable by the first contact upon movement of the pendulum as a result of deceleration of the vehicle to complete an electrical circuit, said electrical circuit including a warning lamp visible from the rear of the road vehicle, and releasable latch means co-operating with the pendulum and operable as the contacts close to retain the pendulum in a position in which the contacts are closed, said releasable latch means comprising a cam on which the pendulum moves, the cam having a portion for retaining the pendulum in position when the contacts close, said cam being carried by the armature of an electro-magnet which is energised by means actuated when the accelerator pedal of the vehicle is depressed, sothat the latch means is released and the first and second contacts open.

References Cited UNITED STATES PATENTS 1,256,134 2/1918 JOeCk. 1,288,128 12/1918 Murray 340-262 1,901,554 3/1933 De Wilde. 2,106,643 1/ 1938 Mellen et a1. 2,671,207 3/ 1954 Marsala 340-52 X 2,704,360 3/1955 Werstein 340-56 2,778,896 1/1957 Tollefsen. 2,831,176 4/1958 Liberto 340-56 X 3,372,386 3/1968 Klinger 3407l X FOREIGN PATENTS 140,896 3/1935 Austria. 613,343 11/ 1948 Great Britain.

JOHN W. CALDWELL, Primary Examiner K. N. LEIMER, Assistant Examiner US. Cl. X.R. 2006l.5; 340-262 

